Display device having integrated metamaterial lens

ABSTRACT

Embodiments related to emissive display device structures having an emissive display element and a metamaterial lens having a plurality of nanoparticles over an emissive surface of the emissive display element to control the angular distribution of light emitted from the emissive display element, displays having such controlled emissive display device structures, systems incorporating such controlled emissive display device structures, and methods for fabricating them are discussed.

CLAIM OF PRIORITY

This application is a Continuation of, and claims priority to, U.S.application Ser. No. 15/381,932, filed Dec. 16, 2016, issued as U.S.Pat. No. 10,416,565, on Sep. 17, 2018, and titled “Display Device HavingIntegrated Metamaterial Lens”, which is incorporated by reference in itsentirety for all purposes.

BACKGROUND

Augmented reality device technology, including augmented realityheadsets and the like, is an area of emerging interest. For suchdevices, it may be desirable to have a display device that providesred-green-blue (RGB) colors (e.g., full color) in a compact package withhigh brightness, collimated light, high contrast, low power, and lowmanufacturing costs to provide high quality products for users.

As such, there is a continual demand for improved display devices forimplementation by augmented reality devices or other devices or systems.It is with respect to these and other considerations that the presentimprovements have been needed. Such improvements may become critical asthe desire to provide high quality micro display devices in a variety ofdevices such as augmented reality devices becomes more widespread.

BRIEF DESCRIPTION OF THE DRAWINGS

The material described herein is illustrated by way of example and notby way of limitation in the accompanying figures. For simplicity andclarity of illustration, elements illustrated in the figures are notnecessarily drawn to scale. For example, the dimensions of some elementsmay be exaggerated relative to other elements for clarity. Further,where considered appropriate, reference labels have been repeated amongthe figures to indicate corresponding or analogous elements. In thefigures:

FIG. 1 is an example setting for providing an example augmented realitydevice;

FIG. 2A is an illustrative diagram of an example system for providing avirtual image;

FIG. 2B is an illustrative diagram of another example system forproviding a virtual image;

FIG. 3 is a cross-sectional view of an example emissive display devicestructure;

FIG. 4 illustrates an expanded view of example the example emissivedisplay device structure;

FIG. 5 illustrates an example micro light emitting diode;

FIGS. 6A, 6B, and 6C illustrate example metamaterial lens metasurfaces;

FIG. 7 illustrates an example metamaterial lens metasurface;

FIG. 8 illustrates an example metamaterial lens metasurface havingnanoparticles with x-shaped cross-sections;

FIG. 9 illustrates an example metamaterial lens metasurface havingboomerang cross-sectional shaped nanoparticles;

FIG. 10 illustrates an example metamaterial lens metasurface havingelliptical cylinder nanoparticles;

FIG. 11 illustrates an example metamaterial lens metasurface on anexample spacer layer;

FIG. 12 is a flow diagram illustrating an example process forfabricating an emissive display device;

FIGS. 13A, 13B, 13C, and 13D are cross-sectional views of exampleemissive display device structures as particular fabrication operationsare performed;

FIG. 14 illustrates a system in which a mobile computing platformemploys an emissive display device structure; and

FIG. 15 is a functional block diagram of a computing device, allarranged in accordance with at least some implementations of the presentdisclosure.

DETAILED DESCRIPTION

One or more embodiments or implementations are now described withreference to the enclosed figures. While specific configurations andarrangements are discussed, it should be understood that this is donefor illustrative purposes only. Persons skilled in the relevant art willrecognize that other configurations and arrangements may be employedwithout departing from the spirit and scope of the description. It willbe apparent to those skilled in the relevant art that techniques and/orarrangements described herein may also be employed in a variety of othersystems and applications other than what is described herein.

Reference is made in the following detailed description to theaccompanying drawings, which form a part hereof, wherein like numeralsmay designate like parts throughout to indicate corresponding oranalogous elements. It will be appreciated that for simplicity and/orclarity of illustration, elements illustrated in the figures have notnecessarily been drawn to scale. For example, the dimensions of some ofthe elements may be exaggerated relative to other elements for clarity.Further, it is to be understood that other embodiments may be utilizedand structural and/or logical changes may be made without departing fromthe scope of claimed subject matter. It should also be noted thatdirections and references, for example, up, down, top, bottom, over,under, and so on, may be used to facilitate the discussion of thedrawings and embodiments and are not intended to restrict theapplication of claimed subject matter. Therefore, the following detaileddescription is not to be taken in a limiting sense and the scope ofclaimed subject matter defined by the appended claims and theirequivalents.

In the following description, numerous details are set forth, however,it will be apparent to one skilled in the art, that the presentinvention may be practiced without these specific details. In someinstances, well-known methods and devices are shown in block diagramform, rather than in detail, to avoid obscuring the present invention.Reference throughout this specification to “an embodiment” or “in oneembodiment” means that a particular feature, structure, function, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. Thus, the appearances ofthe phrase “in an embodiment” in various places throughout thisspecification are not necessarily referring to the same embodiment ofthe invention. Furthermore, the particular features, structures,functions, or characteristics may be combined in any suitable manner inone or more embodiments. For example, a first embodiment may be combinedwith a second embodiment anywhere the two embodiments are not specifiedto be mutually exclusive.

The terms “coupled” and “connected,” along with their derivatives, maybe used herein to describe structural relationships between components.It should be understood that these terms are not intended as synonymsfor each other. Rather, in particular embodiments, “connected” may beused to indicate that two or more elements are in direct physical orelectrical contact with each other. “Coupled” my be used to indicatedthat two or more elements are in either direct or indirect (with otherintervening elements between them) physical or electrical contact witheach other, and/or that the two or more elements co-operate or interactwith each other (e.g., as in a cause an effect relationship).

The terms “over,” “under,” “between,” “on”, and/or the like, as usedherein refer to a relative position of one material layer or componentwith respect to other layers or components. For example, one layerdisposed over or under another layer may be directly in contact with theother layer or may have one or more intervening layers. Moreover, onelayer disposed between two layers may be directly in contact with thetwo layers or may have one or more intervening layers. In contrast, afirst layer “on” a second layer is in direct contact with that secondlayer. Similarly, unless explicitly stated otherwise, one featuredisposed between two features may be in direct contact with the adjacentfeatures or may have one or more intervening features.

Display devices, apparatuses, systems, computing platforms, and methodsare described below related to display devices having integratedmetamaterial lenses.

In some embodiments discussed herein, an emissive display deviceincludes an emissive display element (e.g., a light emitting diode, anorganic light emitting diode, a vertical-cavity surface-emitting laser,etc.) having an emissive surface. For example, the emissive surface maybe any surface either integrated with the emissive display element oradjacent with respect to the emissive display element such that, inoperation, a band of light is emitted through the emissive surface fromthe emissive display element. As used herein, the term emissive surfacemay be a surface through which a band of light is emitted duringoperation from the emissive display element, but the surface need not bein operation to be described or labeled as an emissive surface. Ametamaterial lens is provided over the emissive surface of the emissivedisplay element such that the metamaterial lens includes a plurality ofnanoparticles to control the angular emission of emitted light, and, insome examples, collimate light from the emissive display element. Insome embodiments, the metamaterial lens is on the emissive surface. Inother embodiments, the metamaterial lens is on a material, layer, film,or surface adjacent to the emissive surface. The nanoparticles of themetamaterial lens may include any suitable characteristics to controlthe angular profile of light emitted from the emissive display element.For example, the characteristics (shape, size, placement, pitch, etc.)of the nanoparticles may be selected control the angular emission of orto collimate the particular wavelength band emitted from the emissivedisplay element. Such characteristics are discussed further herein.Furthermore, the nanoparticles discussed herein may be characterized asnano-antennas, nano-blocks, atoms, nano-atoms, or the like.

In another embodiment, an augmented reality device may include anemissive display device as discussed herein, augmented reality opticsoptically coupled to the emissive display device, and an integratedsystem coupled to the emissive display device and configured to provideimage data to the emissive display device. For example, augmentedreality optics may include a visual layer having a prism, a waveguideand first and second holographic beam splitters disposed on oppositeends of the waveguide, or the like. Such an augmented reality device maybe provided in any suitable form factor device such as a headset, smartglasses, or the like. In other embodiments, a display device may includean emissive display device as discussed herein. Such a display devicemay be provided in any suitable form factor device such as a watch, avirtual reality device, a headset, a mobile device such as a smartphone,a phablet, a tablet, a laptop, or the like or as a discrete displaydevice or the like.

FIG. 1 is an example setting 100 for providing an example augmentedreality device 102, arranged in accordance with at least someimplementations of the present disclosure. As shown in FIG. 1, setting100 may include a user 101 interacting with augmented reality device102. For example, augmented reality device 102 may be worn by user 101and, during operation, user 101 may view a virtual image 103. As usedherein the term virtual image refers to an image that is overlaid withrespect to setting 100. As is discussed further herein with respect tosystem 200 below, augmented reality device 102 may include an integratedsystem (e.g., processor, memory, etc.) to provide image data to amicro-display with an integrated metamaterial lens. The image from themicro-display may be provided to a waveguide having holographic beamsplitters on opposite ends thereof to display virtual image 103 to user101 (e.g., over an eye of user 101). For example, the integrated systemand micro-display with integrated metamaterial lens may be providedwithin package 104. Package 104 may be provided as a component ofaugmented reality device 102 such that augmented reality device 102provides virtual image 103 to user 101. For example, virtual image 103may be pertinent to the surroundings viewed by user 101 (e.g., providingdirections, weather information, etc.) while not completely obscuringthe surroundings. In the illustrated example, augmented reality device102 is head mounted on user 101. However, augmented reality device 102may be used by user 101 in any suitable configuration.

FIG. 2A is an illustrative diagram of an example system 200 forproviding virtual image 103, arranged in accordance with at least someimplementations of the present disclosure. As shown in FIG. 2A, system200 may include a micro-display with an integrated metamaterial lens201, a waveguide 203, a holographic beam splitter 204 and a holographicbeam splitter 205 disposed on opposite ends of waveguide 203, and anintegrated system 206. For example, micro-display with integratedmetamaterial lens 201 may include any emissive display elements andmetamaterial lenses discussed herein. In an embodiment, micro-displaywith integrated metamaterial lens 201 may be characterized as acollimated emissive display device. In an embodiment, micro-display 201may provide a red-green-blue projected image 202 (e.g., a highlycollimated projected image) to waveguide 203 and holographic beamsplitter 205 disposed on waveguide 203. For example, micro-display 201and waveguide 203 may be optically coupled such that projected image maybe provided to waveguide. Micro-display 201 and waveguide 203 may beoptically coupled using any suitable configuration such as micro-display201 and waveguide 203 being provided adjacent to one another,micro-display 201 and waveguide 203 being coupled by an opticalwaveguide (not shown), or the like.

As shown, holographic beam splitter 204 and holographic beam splitter205 are provided on opposite ends of waveguide 203 and on a shared side207 of waveguide 203 opposite a side 208 corresponding to the opticalcoupling to micro-display 201. For example, integrated system 206 maygenerate virtual image data for display to user 101. Integrated system206 may generate virtual image data using any suitable technique ortechniques. Micro-display 201 may receive the virtual image data and mayprovide projected image 202. Projected image 202 may enter the end ofwaveguide 203 having holographic beam splitter 204 via side 208 ofwaveguide 203 and projected image 202 may be transmitted by waveguide203 (e.g., via internal reflection of projected image 202 inside thethickness of the glass plate of waveguide) to holographic beam splitter205 such that virtual image 103 is provided within a field of view 209of user 101.

In the context of system 200, it may be advantageous for micro-display201 to provide a highly collimated red-green-blue projected image 202.As is discussed further herein, micro-display 201 may include emissivedisplay elements and metamaterial lenses to control the angular emissionof emitted light and/or to provide a highly collimated red-green-blueprojected image 202. Such devices and configurations may provide for asmall form factor system 200 as a separate, non-integrated, bulkycollimating lens may be not be required. Thereby, the devices discussedherein may provide an advantageously small form factor system 200 thatmay be light weight, more easily packaged into a final device, and thelike.

As discussed, FIG. 2A illustrates an augmented reality systemimplementing a micro-display with an integrated metamaterial lens in thecontext of a holographic beam splitter embodiment. However, themicro-display with an integrated metamaterial lens may be implemented inany suitable augmented reality system or the like.

FIG. 2B is an illustrative diagram of an example system 210 forproviding a virtual image, arranged in accordance with at least someimplementations of the present disclosure. As shown in FIG. 2B, system210 may include micro-display with an integrated metamaterial lens 201,a visual layer 211 having a prism 212, and integrated system 206. Forexample, micro-display with integrated metamaterial lens 201 may includeany emissive display elements and metamaterial lenses discussed herein.In an embodiment, micro-display with integrated metamaterial lens 201may be characterized as a collimated emissive display device. In anembodiment, micro-display 201 may provide highly collimatedred-green-blue projected image 202 to visual layer 211 and prism 212such that prism 212 projects a corresponding image to user 101.

Visual layer 211 and prism 212 may include any suitable materials in anysuitable configuration. For example, visual layer 211 and prism 212 maybe provided optically coupled to micro-display 201 to provide a virtualimage to user 101. For example, integrated system 206 may generatevirtual image data for display to user 101. Micro-display 201 mayreceive the virtual image data and may provide projected image 202.Projected image 202 may enter visual layer 211 and prism 212 may projectthe image to user 101. Furthermore, user 101 may view field of view 209through visual layer and prism 212 such that the projected imageprovides an augmented reality with respect to field of view 209.

In the context of system 210, it may be advantageous for micro-display201 to provide a red-green-blue projected image 202 (e.g., a highlycollimated projected image). As is discussed further herein,micro-display 201 may include emissive display elements and metamateriallenses to control the angular emission of emitted light and/or provide ahighly collimated red-green-blue projected image 202. Such devices andconfigurations may provide for a small form factor system 210 as aseparate, non-integrated, bulky collimating lens may be not be required.Thereby, the devices discussed herein may provide an advantageouslysmall form factor system 210 that may be light weight, more easilypackaged into a final device, and the like.

FIG. 3 is a cross-sectional view of an example emissive display devicestructure 300, arranged in accordance with at least some implementationsof the present disclosure. As shown, emissive display device structure300 may include a substrate 321, an isolation layer 322, emissivedisplay elements 301, 302, 303, 304, 305, 306, 307, 308, 309 andcorresponding metamaterial lenses 311, 312, 313, 314, 315, 316, 317,318, 319 over emissive display elements 301, 302, 303, 304, 305, 306,307, 308, 309, respectively. Metamaterial lenses 311-319 may control theangular emission of emitted light from emissive display elements301-309. Metamaterial lenses 311-319 may be characterized as photonicmetamaterial lenses, collimating lenses, metasurface collimating lenses,or the like. Metamaterial lenses 311-319 may include any nanoparticlesas discussed further herein below.

As shown, emissive display elements 301-309 may include red (R) emissivedisplay elements 301, 304, 307, green (G) emissive display elements 302,305, 308, and blue (B) emissive display elements 303, 306, 309 arrayedover substrate 321. From a top-down perspective, emissive displayelements 301-309 and corresponding metamaterial lenses 311-319 may bearrayed over substrate 321 in a grid pattern or the like to provide ahigh pixel density emissive display device. Furthermore, from a top-downperspective emissive display elements 301-309 may be about one to 10microns wide by about one to 10 microns long although any suitable sideof emissive display elements 301-309 may be used.

Substrate 321 may include any suitable material, materials, or devices.For example, substrate 321 may be a wafer or carrier or the like suchthat substrate 321 is a silicon wafer, a sapphire wafer, a galliumarsenide wafer, a gallium nitride wafer, a silicon carbide wafer, or thelike. In other examples, particularly in the context of implementation,substrate 321 may be a back plane of a display device including a drivercircuit or circuitry, a driver circuit, or the like. For example,substrate 321 may include a driver circuit provided on a back plane, athin film transistor device structure, or the like. As used herein, theterm substrate may indicate any layer or layers adjacent to emissivedisplay elements 301-309. For example, the substrate may include acarrier, a buffer or nucleation layer, isolation or dielectric layers,driver circuitry, back planes, support structures, packaging structures,or the like. Furthermore, isolation layer 322 may include any suitablematerial or materials for electrically isolating emissive displayelements 301-309 such as insulator materials (e.g., silicon dioxide,silicon nitride, aluminum oxide, doped silicon oxide, etc.) or the like.In some embodiments, isolation layer 322 is a transparent dielectricmaterial.

Emissive display elements 301-309 may include any type or combination oftypes of emissive display elements such as, for example, light emittingdiodes, micro light emitting diodes, organic light emitting diodes,vertical-cavity surface-emitting lasers, or the like. In an embodiment,emissive display elements 301-309 are all of the same type (e.g., lightemitting diodes, micro light emitting diodes, organic light emittingdiodes, a vertical-cavity surface-emitting lasers, etc.) and provide thesame color band of light. In an embodiment, emissive display elements301-309 are all of the same type but provide different color bands oflight (e.g., red, green, blue). In an embodiment, emissive displayelements 301-309 include different types of emissive devices. Forexample, one or more bands of light may be provided by a different typeof emissive devices.

Metamaterial lenses 311-319, as discussed, may include nanoparticles tocontrol the angular emission of emitted light from emissive displayelements 301-309. In an embodiment, metamaterial lenses 311-319collimate light from emissive display elements 301-309. Metamateriallenses 311-319 may be characterized as 2D metamaterial lenses, forexample. The nanoparticles of metamaterial lenses 311-319 may be anysuitable material or materials that may alter the light emitted fromemissive display elements 301-309 such as, for example, one or more ofsilicon, titanium oxide, gallium phosphide, diamond, or the like.Furthermore, as illustrated in detail herein below, the nanoparticles ofmetamaterial lenses 311-319 may have any suitable cross-sectional shapeor shapes such as, for example, a circle, an oval, a square, arectangle, a cross, a boomerang shape, or the like.

As discussed, groups of emissive display elements 301-309 may providedifferent bands of colors of light such as emissive display elements301, 304, 307 providing a red (R) band, emissive display elements 302,305, 308 providing a red (R) band, and emissive display elements 303,306, 309 providing a blue (R) band, or the like. In such examples,corresponding metamaterial lenses 311-319 may have differentcharacteristics based on the corresponding band of light of thecorresponding emissive display elements 301-309. For example, thenanoparticles of each of metamaterial lenses 311, 314, 317, metamateriallenses 312, 315, 318, and metamaterial lenses 313, 316, 319 may havedifferent characteristics (e.g., shape, size, placement, pitch, etc.)selected based on the band of light of the corresponding emissivedisplay elements 301-309 to control the angular emission of emittedlight. In an embodiment, the nanoparticles may be selected to providehighly collimated light for the particular band of light.

The difference or differing characteristic(s) of the nanoparticlesbetween groups of metamaterial lenses (e.g., between lenses 311, 314,317, lenses 312, 315, 318, and lenses 313, 316, 319) may include, forexample, the cross-sectional shape of the nanoparticles, the size ofeach nanoparticle or the average sizes of the nanoparticles, the spacingor pitch of the nanoparticles or the average spacing or pitch of thenanoparticles, or the like.

In an embodiment, the nanoparticles of metamaterial lenses 311, 314, 317have a different cross-sectional shape than those of one or both of thenanoparticles of metamaterial lenses 312, 315, 318 and the nanoparticlesof metamaterial lenses 313, 316, 319. For example, the cross-sectionalshapes of one group may differ from the other two or all three may havedifferent cross-sectional shapes. The difference in cross-sectionalshapes may be among all nanoparticles of the respective groups or only aportion of the nanoparticles of the respective lenses. For example, agroup of metamaterial lenses may have a single cross-sectional shapetype (of the same or differing sizes) or mixed cross-sectional shapeswith only a particular cross-sectional shape differing from those ofother group(s) of lenses.

In an embodiment, the nanoparticles of metamaterial lenses 311, 314, 317have an average cross-sectional size different than that of the averagecross-sectional size of the nanoparticles of one or both of metamateriallenses 312, 315, 318 and the nanoparticles of metamaterial lenses 313,316, 319. The average cross-sectional size may be any suitable measuresuch as an average area of the nanoparticles, an average length or widthof the nanoparticles, or the like. For example, the averagecross-sectional size of one group may differ from the other two or allthree may have different average cross-sectional sizes.

In an embodiment, the nanoparticles of metamaterial lenses 311, 314, 317have an average pitch or spacing different than that of the averagepitch or spacing of the nanoparticles of one or both of metamateriallenses 312, 315, 318 and the nanoparticles of metamaterial lenses 313,316, 319. For example, the average pitch or spacing of one group maydiffer from the other two or all three may have different averagepitches or spacings. The average pitch or spacing may be any suitablemeasure such as an average of the distances between like features of thenanoparticles, an average of the distances between like features ofgroups of nanoparticles, an average of the distances betweennanoparticles, a coverage density of the nanoparticles (e.g., a ratio ofthe area covered by the nanoparticles to a total area including theareas covered and uncovered by the nanoparticles), or the like.

As discussed, metamaterial lenses 311-319 are disposed over emissivedisplay elements 301-309 to control the angular emission of emittedlight from emissive surfaces of emissive display elements 301-309.Furthermore, may be any type or combination of types of emissive displayelements such as light emitting diodes, organic light emitting diodes,vertical-cavity surface-emitting lasers, or the like.

FIG. 4 illustrates an expanded view 400 of example emissive displaydevice structure 300, arranged in accordance with at least someimplementations of the present disclosure. As shown in FIG. 4, emissivedisplay elements 301 may include an emissive surface 411, emissivedisplay elements 302 may include an emissive surface 412, and emissivedisplay elements 303 may include an emissive surface 413. Emissivedisplay elements 304-309 may include corresponding emissive surfaces. Asshown, in an embodiment, emissive surfaces 411, 412, 413 may be asurface of emissive display elements 301, 302, 303 opposite substrate321. Also as shown, metamaterial lenses 311, 312, 313 may be overemissive surfaces 411, 412, 413 and portions of isolation layer 322 toprovide overhangs as illustrated with respect to overhang 421. In otherembodiments, metamaterial lenses 311, 312, 313 may be over a portion ofone or more of emissive surfaces 411, 412, 413 such that metamateriallenses 311, 312, 313 do not fully cover emissive surfaces 411, 412, 413.

Also as shown, metamaterial lenses 311, 312, 313 may provide control ofthe angular emission of light 401, 402, 403, which, as in theillustrated example, may be red light, green light, and blue light,respectively. In an embodiment, metamaterial lenses 311, 312, 313provide highly collimated red, green and blue light. As shown, in anembodiment, metamaterial lenses 311, 312, 313 may collimate lightemitted from emissive display elements 301, 302, 303 that may otherwisedisperse in a lambertion wide angle pattern. For example, emissivedisplay elements 301, 302, 303 may have a reduced size as metamateriallenses 311, 312, 313 more efficiently controls the angular emission oflight. Furthermore, such collimation may be achieved without substantialenergy loss by metamaterial lenses 311, 312, 313.

As discussed, emissive display elements 301-309 may include any type ortypes of emissive display elements such as, for example, light emittingdiodes, micro light emitting diodes, organic light emitting diodes, avertical-cavity surface-emitting lasers, or the like. Furthermore,metamaterial lenses 311-319 may be disposed on any structure or emissivesurface or the like of emissive display elements 301-309 such as agallium nitride layer of a micro LED, an aluminum indium galliumphosphide layer of a micro LED, any suitable layer of emissive displayelements 301-309 or layer disposed on emissive display elements 301-309.

FIG. 5 illustrates an example micro light emitting diode 500, arrangedin accordance with at least some implementations of the presentdisclosure. As shown in FIG. 5, micro light emitting diode 500 mayinclude substrate 321, an electron transport layer 501, an activeemission layer 502, a hole transport layer 503, and a transparentelectrode 504. For example, in the context of micro light emitting diode500, substrate 321 may include a buffer layer or nucleation layer,electron transport layer 501 may be n-doped gallium nitride, activeemission layer 502 may include one or more layers of indium galliumnitride and one or more layers of gallium nitride, hole transport layer503 may be p-doped gallium nitride, and transparent electrode 504 may beindium tin oxide.

For example, the light emitted by micro light emitting diode 500 may becontrolled by the indium concentration in the indium gallium nitridelayer(s) of active emission layer 502. For example, an indiumconcentration of about 41% in the indium gallium nitride layer(s) mayprovide a red color micro LED, an indium concentration of about 37% inthe indium gallium nitride layer(s) may provide a green color micro LED,and an indium concentration of about 20% in the indium gallium nitridelayer(s) may provide a blue color micro LED. As shown, micro lightemitting diode 500 may include an emissive surface 505 such that lightis emitted through at least emissive surface 505 during operation ofmicro light emitting diode 500.

As discussed, metamaterial lenses 311-319 include nanoparticles thatcontrol the angular emission of emitted light emitted from emissivedisplay elements 301-309. For example, metamaterial lenses 311-319 mayinclude nanoparticles having a periodic, cellular structure withsubwavelength periodicity that interact with visible light. Themetamaterial may be described by an effective medium approximation that,when reacting to an external excitation, are effectively homogeneouswith corresponding effective permittivity. The optical properties ofsuch metamaterials (e.g., photonic metamaterials) may arise from aninteraction similar to that of atoms or ions in a solid medium. Forexample, metamaterials may have a negative relative permittivity thatmay provide for metamaterial lenses 311-319.

As discussed, metamaterial lenses 311-319, which may be characterized asa metasurface lens, may bend light based on the nanoparticles of themetamaterial. For example, metamaterial lenses 311-319 may include aperiodic two-dimensional arrangement of nanoparticles having a thicknessand periodicity that are small (e.g., 5 to 10 times less than) withrespect to the wavelength of light. For example, for visible light, thewavelength may be in the range of about 400 to 700 nanometers.Furthermore, metamaterial lenses 311-319 may have inhomogeneouselectromagnetic properties due to the subwavelength details of theirstructure to control light and provide, for example, collimation.Discussion now turns to example metamaterial lens metasurfaces withexample nanoparticles. In the following, the discussed nanoparticles maybe any suitable material or materials such as silicon, titanium oxide,gallium phosphide, diamond, or the like.

FIGS. 6A, 6B, and 6C illustrate example metamaterial lens metasurfaces,arranged in accordance with at least some implementations of the presentdisclosure. As shown in FIG. 6A, metamaterial or metasurface 602includes nanoparticles 603 on a substrate 601 and metamaterial ormetasurface 604 includes nanoparticles 605 on a substrate 601. In thecontext of FIGS. 6A-C, 7, 8, 9, 10, and 11, substrate 601 may be anysuitable surface for forming a metamaterial or metasurface such as anemissive surface of an emissive display element, a buffer layer over anemissive display element, or the like. Furthermore, the metamaterials ormetasurfaces of nanoparticles discussed with respect to FIGS. 6A-C, 7,8, 9, 10, and 11 may be implemented in any metamaterial lens discussedherein such as emissive display elements 301, 304, 307, emissive displayelements 302, 305, 308, and/or emissive display elements 303, 306, 309either alone or in combination.

As shown in FIG. 6A, metamaterial 602 includes nanoparticles 603 havinga square or rectangular cross-sectional shape (e.g., a three-dimensionalcuboid shape). In an embodiment, metamaterial 602 includes nanoparticleshaving a variety of sizes such that nanoparticles 603 have substantiallysquare or rectangular cross-section and widths (e.g., w₁, w₂, w₃, w₄,w₅, w₆), please refer to FIG. 6B, or lengths (not labeled but extendingin the y-direction) that vary across metamaterial 602. Such widths orlengths may be any suitable values and may be based on the wavelength oflight for which they are implemented to control the angular emission ofemitted light as discussed herein. For example, for a red emissivedisplay element, nanoparticles 603 may have lengths or widths in therange of about 60 to 150 nanometers, for a green emissive displayelement, nanoparticles 603 may have lengths or widths in the range ofabout 45 to 120 nanometers, and for a blue emissive display element,nanoparticles 603 may have lengths or widths in the range of about 40 to120 nanometers. As discussed, in some embodiments, nanoparticles 603have a square cross-sectional shape and, in other embodiments,nanoparticles 603 have a rectangular cross-sectional shape. Furthermore,in the illustrated embodiment, nanoparticles 603 have varying widthsand/or lengths. In an embodiment nanoparticles 603 of metamaterial 602are all substantially the same size.

Also as shown in FIG. 6A, metamaterial 604 includes nanoparticles 605having a circular or oval cross-sectional shape (e.g., nanoparticles 605are cylinders or elliptical cylinders). In an embodiment, metamaterial604 includes nanoparticles having a variety of sizes such thatnanoparticles 605 have substantially circular or oval cross-section anddiameters (e.g., d₁, d₂, d₃, d₄, d₅, d₆), please refer to FIG. 6C, orlengths or widths or the like that vary across metamaterial 604. Suchdiameters or lengths or widths may be any suitable values and may bebased on the wavelength of light for which they are implemented tocontrol the angular emission of emitted light as discussed herein. Forexample, for a red emissive display element, nanoparticles 605 may havediameters or lengths or widths in the range of about 60 to 150nanometers, for a green emissive display element, nanoparticles 605 mayhave diameters or lengths or widths in the range of about 45 to 120nanometers, and for a blue emissive display element, nanoparticles 605may have diameters or lengths or widths in the range of about 40 to 120nanometers.

Nanoparticles 603, 605 may have any suitable thickness such as athickness of about 2 to 10 times less than the wavelength of light forwhich they are implemented to control the angular emission of emittedlight as discussed herein. For example, for a red emissive displayelement, nanoparticles 603 may have a thickness of about 60 to 400nanometers, for a green emissive display element, nanoparticles 603 mayhave a thickness of about 45 to 300 nanometers, and for a blue emissivedisplay element, nanoparticles 603 may have a thickness of about 40 to270 nanometers. In an embodiment, nanoparticles 603, 605 have athickness in the range of about 200 to 400 nanometers. In an embodiment,nanoparticles 603, 605 are high aspect ratio nanoparticles having anaspect ratio of a height of the nanoparticle to a width (or length ordiameter or the like) of the nanoparticle of at least 2.5.

FIG. 7 illustrates an example metamaterial lens metasurface 702,arranged in accordance with at least some implementations of the presentdisclosure. As shown in FIG. 7, metamaterial or metasurface 702 includesnanoparticles 703, 704, 705, 706 on substrate 601. As discussed,metamaterial lens metasurface 702 of nanoparticles 703, 704, 705, 706may be implemented in any metamaterial lens discussed herein. As shownin FIG. 7, nanoparticles 703, 704, 705, 706 may be rectangular cuboidshaving the same or varying cross-sectional dimensions and/or varyingorientations. Nanoparticles 703, 704, 705, 706 may have any suitabledimensions. As discussed, the dimensions of nanoparticles ofmetamaterial lenses may be based on the wavelength of light themetamaterial lens is controlling. In an embodiment, nanoparticles 703,704, 705, 706 may have a height (h) of about the wavelength of lightdivided by two (i.e., h≈λ/2), a first cross-sectional dimension (l_(x))of about the wavelength of light divided by seven (i.e., l_(x)≈λ/7), anda second cross-sectional dimension (l_(y)) of about the wavelength oflight divided by five (i.e., l_(x)≈λ/5) as illustrated with respect tonanoparticle 703. For example, for a red emissive display element,nanoparticles 703, 704, 705, 706 may have a height (h) in the range ofabout 300 to 400 nanometers, a first cross-sectional dimension (l_(x))in the range of about 80 to 100 nanometers, and a second cross-sectionaldimension (l_(y)) in the range of about 120 to 150 nanometers. For agreen emissive display element, nanoparticles 703, 704, 705, 706 mayhave a height (h) in the range of about 250 to 300 nanometers, a firstcross-sectional dimension (l_(x)) in the range of about 60 to 75nanometers, and a second cross-sectional dimension (l_(y)) in the rangeof about 95 to 120 nanometers. For a blue emissive display element,nanoparticles 703, 704, 705, 706 may have a height (h) in the range ofabout 210 to 260 nanometers, a first cross-sectional dimension (l_(x))in the range of about 60 to 75 nanometers, and a second cross-sectionaldimension (l_(y)) in the range of about 85 to 110 nanometers.

Also as shown, nanoparticles 703, 704, 705, 706 may provide a repeatingunit 707 that is repeated across metasurface 702. For example, repeatingunit 707 may have a pitch (P) of about the wavelength of light dividedby two (i.e., P≈λ/2). For example, for a red emissive display element,the pitch may be in the range of about 300 to 400 nanometers, for agreen emissive display element, the pitch may be in the range of about250 to 300 nanometers, and for a blue emissive display element, thepitch may be in the range of about 210 to 260 nanometers. In someembodiments, nanoparticles 703, 704, 705, 706 may have dimensions asdiscussed with respect to nanoparticles 603 of metamaterial 602.

FIG. 8 illustrates an example metamaterial lens metasurface 802 havingnanoparticles with x-shaped cross-sections, arranged in accordance withat least some implementations of the present disclosure. As shown inFIG. 8, metamaterial or metasurface 802 includes nanoparticles 803 onsubstrate 601. As discussed, metamaterial lens metasurface 802 ofnanoparticles 803 may be implemented in any metamaterial lens discussedherein. As shown in FIG. 8, nanoparticles 803 may have a cross-sectionalshape of a cross or an x-shape. For example, nanoparticles 803 may eachinclude two intersecting bars that intersect at approximately theirmidpoints, are perpendicular, and are approximately the same length.However, in other examples, nanoparticles 803 may have intersecting barsof different lengths, bars that intersect at non-mid points of one orboth bars, or bars that are not perpendicular. In an embodiment,nanoparticles 803 are approximately the same size, shape and orientationand are arrayed as a grid. In other embodiments, nanoparticles may havedifferent sizes, shapes, orientations, or varying pitches.

Nanoparticles 803 may have any suitable dimensions. As discussed, thedimensions of nanoparticles of metamaterial lenses may be based on thewavelength of light the metamaterial lens is controlling. In anembodiment, nanoparticles 803 may have a height (h) of about thewavelength of light divided by two (i.e., h≈λ/2), an overall length orbar length (L) of about the wavelength of light divided by about five to10 (i.e., L≈λ/10−λ/5), and bar width of (W_(B)) that is in the range ofabout one-fifth to about one-half of the overall bar length (i.e.,W_(B)=k*L, k≈0.2-0.5) Also as shown, nanoparticles 803 may be repeatedacross metasurface 802 at a pitch (P) of about the wavelength of lightdivided by two (i.e., P≈λ/2).

In an embodiment, metasurface 802 may be provided over an emissivedisplay element that emits a red band and the wavelength may be in therange of about 620-750 nm. In an embodiment, metasurface 802 may beprovided over an emissive display element that emits a green band andthe wavelength may be in the range of about 495-570 nm. In anembodiment, metasurface 802 may be provided over an emissive displayelement that emits a blue band and the wavelength may be in the range ofabout 450-495 nm. For example, for a red emissive display element,nanoparticles 803 may have an overall length in the range of about 60 to150 nanometers and a pitch and/or height in the range of about 300 to400 nanometers, for a green emissive display element, nanoparticles 603may have an overall length in the range of about 45 to 120 nanometersand a pitch and/or height in the range of about 250 to 300 nanometers,and for a blue emissive display element, nanoparticles 603 may have anoverall length in the range of about 40 to 120 nanometers and a pitchand/or height in the range of about 200 to 250 nanometers.

FIG. 9 illustrates an example metamaterial lens metasurface 902 havingboomerang cross-sectional shaped nanoparticles, arranged in accordancewith at least some implementations of the present disclosure. As shownin FIG. 9, metamaterial or metasurface 902 includes nanoparticles 903 onsubstrate 601. As discussed, metamaterial lens metasurface 902 ofnanoparticles 903 may be implemented in any metamaterial lens discussedherein. As shown in FIG. 9, nanoparticles 903 may have a cross-sectionalshape of a boomerang or a kidney bean shape or the like. For example,nanoparticles 903 may each include two extending legs 904, 905 withrounded ends that are at an angle (a) with respect to the centerlines ofextending legs 904, 905. Furthermore, at the intersection of extendinglegs 904, 905, nanoparticles 903 include a curved interior joint 906 anda curved exterior joint 907. As shown, extending legs 904, 905 mayintersect at approximately their midpoints, be approximately the samelength, and intersect at an obtuse angle. However, in other examples,nanoparticles 903 may have extending legs 904, 905 of different lengths,extending legs 904, 905 that intersect at non-mid points of one or bothof extending legs 904, 905, or extending legs 904, 905 that are at rightor acute angles. In an embodiment, nanoparticles 903 are approximatelythe same size, shape and orientation and are arrayed as a grid. In otherembodiments, nanoparticles 903 may have different sizes, shapes,orientations, or varying pitches. For example, as shown in FIG. 9, theangle of intersection of extending legs 904, 905 among nanoparticles 903may be varied across metasurface 902 such that the angle of intersectionis acute in some nanoparticles 903 and right or obtuse in others.

Nanoparticles 903 may have any suitable dimensions. As discussed, thedimensions of nanoparticles of metamaterial lenses may be based on thewavelength of light the metamaterial lens is controlling. In anembodiment, nanoparticles 903 may have a height (h) of about thewavelength of light divided by two (i.e., h≈λ/2), an overall length (L)of about the wavelength of light divided by about five to 10 (i.e.,L≈λ/10−λ/5), and leg width of (W_(L)) that is in the range of aboutone-fifth to about one-half of the overall bar length (i.e., W_(L)=k*L,k≈0.2−0.5) Also as shown, nanoparticles 903 may be repeated acrossmetasurface 902 at a pitch (P) of about the wavelength of light dividedby two (i.e., P≈λ/2). As discussed herein, metasurface 902 may beprovided over an emissive display element that emits a red band(λ≈620-750 nm), a green band (λ≈495-570 nm), or a blue band (λ≈450-495nm). For example, for a red emissive display element, nanoparticles 903may have an overall length in the range of about 60 to 150 nanometersand a pitch and/or height in the range of about 300 to 400 nanometers,for a green emissive display element, nanoparticles 903 may have anoverall length in the range of about 45 to 120 nanometers and a pitchand/or height in the range of about 250 to 300 nanometers, and for ablue emissive display element, nanoparticles 903 may have an overalllength in the range of about 40 to 120 nanometers and a pitch and/orheight in the range of about 200 to 250 nanometers.

FIG. 10 illustrates an example metamaterial lens metasurface 1002 havingelliptical cylinder nanoparticles, arranged in accordance with at leastsome implementations of the present disclosure. As shown in FIG. 10,metamaterial or metasurface 1002 includes nanoparticles 1003 onsubstrate 601. As discussed, metamaterial lens metasurface 1002 ofnanoparticles 1003 may be implemented in any metamaterial lens discussedherein. As shown in FIG. 10, nanoparticles 1003 may be ellipticalcylinders (e.g., nanoparticles 1003 are elliptical or oval incross-section) having the same or varying cross-sectional dimensionsand/or varying orientations. Nanoparticles 1003 may have any suitabledimensions. As discussed, the dimensions of nanoparticles ofmetamaterial lenses may be based on the wavelength of light themetamaterial lens is controlling. In an embodiment, nanoparticles 1003may have a height (h) of about the wavelength of light divided by two(i.e., h≈λ/2), a first cross-sectional dimension or diameter (D_(x)) ofabout the wavelength of light divided by seven (i.e., l_(x)≈λ/7), and asecond cross-sectional dimension or diameter (D_(y)) of about thewavelength of light divided by five (i.e., l_(x)≈λ/5).

As shown, nanoparticles 1003 may be provided within metamaterial lensmetasurface 1002 at varying cross-sectional dimensions and ororientations (as defined by the degree angle, θ, of a long axis of thenanoparticle varies from a particular direction along substrate 601 suchas the x-direction as illustrated). For example, in the context of a redband of light nanoparticles 1003 may have a first cross-sectionaldimension or diameter (D_(x)) in the range of about 60 to 150 nanometersand a second cross-sectional dimension or diameter (D_(y)) in the rangeof about 20 to 100 nanometers. In the context of a green band of lightnanoparticles 1003 may have a first cross-sectional dimension ordiameter (D_(x)) in the range of about 45 to 120 nanometers and a secondcross-sectional dimension or diameter (D_(y)) in the range of about 15to 80 nanometers. In the context of a blue band of light nanoparticles1003 may have a first cross-sectional dimension or diameter (D_(x)) inthe range of about 40 to 120 nanometers and a second cross-sectionaldimension or diameter (D_(y)) in the range of about 15 to 50 nanometers.

FIG. 11 illustrates an example metamaterial lens metasurface 1102 on anexample spacer layer, arranged in accordance with at least someimplementations of the present disclosure. As shown in FIG. 11,metamaterial or metasurface 1102 includes nanoparticles 1103 on a spaceror buffer layer 1104, which is on substrate 601. As discussed,metamaterial lens metasurface 1102 of nanoparticles 1103 may beimplemented in any metamaterial lens discussed herein. Furthermore, FIG.11 illustrates an embodiment in which buffer layer 1104 is disposed onthe emissive display element (e.g., any of emissive display elements301-309). Such embodiments are also discussed further herein withrespect to FIGS. 13A-13D.

As shown in FIG. 11, nanoparticles 1103 may be rectangular cuboids orcubes or the like (e.g., nanoparticles 1103 are square or rectangular incross-section). In the illustrated example, nanoparticles 1103 havesubstantially the same cross-sectional dimensions, height (h),orientation and are arrayed in a grid pattern over buffer layer 1104. Inother examples, nanoparticles may have varying cross-sectionaldimensions, orientations, and/or varying orientations. Nanoparticles11103 may have any suitable dimensions such as those discussed withrespect to nanoparticles 603, 703-706. As discussed, the dimensions ofnanoparticles of metamaterial lenses may be based on the wavelength oflight the metamaterial lens is controlling. In an embodiment,nanoparticles 1103 may have a height (h) of about the wavelength oflight divided by two (i.e., h≈λ/2) and cross-sectional length and width(1, w) in the range of about the wavelength of light divided by five to10 (i.e., 1≈w≈λ/10−λ/5).

Also as shown, nanoparticles 1103 may be repeated or arrayed acrossmetasurface 1102 at a pitch (P) of about the wavelength of light dividedby two (i.e., P≈λ/2). As discussed herein, metasurface 1102 may beprovided over buffer layer 1104, which may be disposed over an emissivedisplay element that emits a red band (λ≈620-750 nm), a green band(λ≈495-570 nm), or a blue band (λ≈450-495 nm). For example, for a redemissive display element, nanoparticles 1103 may have a length and widthin the range of about 60 to 150 nanometers and a pitch and/or height inthe range of about 300 to 400 nanometers, for a green emissive displayelement, nanoparticles 1103 may have a length and width in the range ofabout 45 to 120 nanometers and a pitch and/or height in the range ofabout 250 to 300 nanometers, and for a blue emissive display element,nanoparticles 1103 may have an overall length in the range of about 40to 120 nanometers and a pitch and/or height in the range of about 200 to250 nanometers.

Buffer layer 1104 may include any suitable material or material such assilicon dioxide, silicon nitride, aluminum oxide, doped silicon oxide,or the like. Furthermore, buffer layer 1104 may have any suitablethickness (t) such as a thickness in the range of about 20 to 400nanometers. Buffer layer 1104 may provide a substantially flat surfacefor nanoparticles 1103 as well as a predefined surface material fornanoparticles such as nanoparticles 1103. Such a predefined surface mayadvantageously provide more predictable characteristics for theimplementation of metasurfaces discussed herein.

FIG. 12 is a flow diagram illustrating an example process 1200 forfabricating an emissive display device, arranged in accordance with atleast some implementations of the present disclosure. For example,process 1200 may be implemented to fabricate any emissive display devicestructure discussed herein such as emissive display device structure 300or emissive display device structure 1304. In the illustratedimplementation, process 1200 may include one or more operations asillustrated by operations 1201-1204. However, embodiments herein mayinclude additional operations, certain operations being omitted, oroperations being performed out of the order provided.

Process 1200 may begin at operation 1201, where emissive displayelements may be fabricated over a substrate. The emissive displayelements may be fabricated using any suitable technique or techniques.For example, the emissive display elements may include one or more oflight emitting diodes, micro light emitting diodes, organic lightemitting diodes, a vertical-cavity surface-emitting lasers, or the like.Furthermore, the emissive display elements may include a combination ofred, green, and blue emissive display elements arrayed over a substrate.The substrate may include any suitable substrate such as a wafer orcarrier or a back plane of a display device including a driver circuitor circuitry. For example, process 1200 may provide fabricationtechniques implemented after emissive display elements are formed on aback plane or driver circuit or the like. In an embodiment, one or moreof emissive display elements 301-309 may be disposed fabricated oversubstrate 321 as discussed herein with respect to FIG. 13A.

Process 1200 may continue at operation 1202, where a spacer or bufferlayer may be disposed over emissive surfaces of the emissive displayelements. The spacer or buffer layer may include any suitable materialor materials substantially transparent to light emitted by the emissivedisplay elements. For example, the spacer or buffer layer may be any ora combination of silicon dioxide, silicon nitride, aluminum oxide, dopedsilicon oxide, or the like. Furthermore, the spacer or buffer layer maybe disposed over the emissive surfaces of the emissive display elementsusing any suitable technique or techniques at any suitable thicknesssuch as a thickness in the range of 50 to 400 nanometers. In anembodiment, the a spacer or buffer layer is disposed by a lowtemperature deposition at a temperature no greater than 400° C. Such lowtemperature processing may be advantageous in that it does not disturbpreviously fabricated emissive display elements. The spacer or bufferlayer may provide a substantially flat surface for subsequentfabrication of metamaterial lenses as well as a controlled materialinterface (e.g., the spacer or buffer may be selected whereas theemissive surface may not be selectable) for the metamaterial lenses. Inan embodiment, a spacer or buffer layer may be disposed over emissivesurfaces of the emissive display elements as discussed herein withrespect to FIG. 13B. In other embodiments, no spacer or buffer layer maybe applied as discussed herein.

Process 1200 may continue at operation 1203, where an optical coatinglayer may be disposed over the emissive surfaces of the emissive displayelements. The optical coating layer may include any suitable material ormaterials such as one or more of silicon, titanium oxide, galliumphosphide, diamond. The optical coating layer provided at operation 1203does not have the properties of metamaterials as discussed herein (e.g.,such properties may be provided at operation 1204). The term opticalcoating layer as used herein refers to a layer, film, or the like of amaterial that may provide, after patterning, a metamaterial lens asdiscussed herein. The optical coating layer may be formed using anysuitable technique or techniques such as atomic layer deposition, plasmaenhanced atomic layer deposition, chemical vapor deposition, plasmaenhanced chemical vapor deposition, physical sputtering deposition, orthe like. In an embodiment, disposing the optical coating layer isperformed by a low temperature deposition at a temperature no greaterthan 400° C. Such low temperature processing may be advantageous in thatit does not disturb previously fabricated emissive display elements. Insome examples, the optical coating layer is disposed on the spacer orbuffer layer discussed with respect to operation 1202. In otherexamples, the optical coating layer is disposed on the emissive surfacesof the emissive display elements as illustrated with respect to FIG. 3and elsewhere herein. In an embodiment, an optical coating layer may bedisposed over the emissive surfaces of the emissive display elements asdiscussed herein with respect to FIG. 13C.

Process 1200 may continue at operation 1204, where the optical coatinglayer may be patterned to form metamaterial lenses having nanoparticlesas discussed herein. The optical coating layer may be patterned usingany suitable technique or techniques such as deep ultravioletlithography, extreme ultraviolet lithography, nanoimprint lithography,electron beam lithography, or the like. The metamaterial lenses formedat operation may include any metamaterial lenses and any nanoparticlesdiscussed herein. In an embodiment, the emissive display elementsfabricated at operation 1201 include an emissive display element to emita red band of light, an emissive display element to emit a green band oflight, and an emissive display elements to emit a blue band of light. Insuch an embodiment, the optical coating layer disposed at operation 1203may be disposed over emissive surfaces of the emissive display elementsand patterning the optical coating layer may include formingcorresponding metamaterial lenses over the red, green, and blue emissivedisplay elements such that the nanoparticles of the metamaterial lensover the red emissive display elements have an average cross-sectionalsize that is greater than the average cross-sectional size of thenanoparticles of the metamaterial lens over the green emissive displayelements, which is greater than the average cross-sectional size of thenanoparticles of the metamaterial lens over the blue emissive displayelements. Such nanoparticles may have the same cross-sectional shapes orthey may be different. In an embodiment, the optical coating layer maybe patterned to form metamaterial lenses having nanoparticles asdiscussed herein with respect to FIG. 13C.

Process 1200 may be utilized to generate any emissive display devicestructure as discussed herein such as those discussed with respect toemissive display device structure 300 or emissive display devicestructure 1304 or the like.

FIGS. 13A, 13B, 13C, and 13D are cross-sectional views of exampleemissive display device structures as particular fabrication operationsare performed, arranged in accordance with at least some implementationsof the present disclosure. As shown in FIG. 13A, an emissive displaydevice structure 1301 includes substrate 321, isolation layer 322, andemissive display elements 301-309 fabricated over substrate 321.Emissive display elements 301-309 may be fabricated over substrate 321using any suitable technique or techniques. Emissive display elements301-309 may include any combination of light emitting diodes, microlight emitting diodes, organic light emitting diodes, a vertical-cavitysurface-emitting lasers, or the like as discussed herein and emissivedisplay elements 301-309 may include a combination of red, green, andblue emissive display elements arrayed over substrate 321. Substrate 321may include any suitable substrate such as a wafer or carrier or a backplane of a display device including a driver circuit or circuitry. Alsoas shown, isolation layer 322 may be provided on substrate 321 andadjacent to emissive display elements 301-309. Isolation layer 322 maybe formed using any suitable technique or techniques either before orafter the fabrication of emissive display elements 301-309. In anembodiment, isolation layer 322 may be provided having trenches thereinand emissive display elements 301-309 may be formed in the trenches.

FIG. 13B illustrates an emissive display device structure 1302 similarto emissive display device structure 1301, after the formation of bufferlayer 1311. Buffer layer 1311 may include any suitable material ormaterials such as silicon dioxide, silicon nitride, aluminum oxide,doped silicon oxide, or the like. Buffer layer 1311 may be disposed onemissive display elements 301-309 and exposed portions of isolationlayer 322 using any suitable technique or techniques such as atomiclayer deposition, plasma enhanced atomic layer deposition, chemicalvapor deposition, plasma enhanced chemical vapor deposition, physicalsputtering deposition. In an embodiment, forming buffer layer 1311includes a low temperature deposition at a temperature no greater than400° C. Buffer layer 1311 may have any suitable thickness such as athickness in the range of about 50 to 400 nanometers. Buffer layer 1311may provide a substantially flat surface for subsequent fabrication ofmetamaterial lenses as well as a controlled material interface for themetamaterial lenses.

FIG. 13C illustrates an emissive display device structure 1303 similarto emissive display device structure 1302, after the formation ofoptical coating layer 1312. Optical coating layer 1312 may include anysuitable material or materials and any suitable thickness for theformation of metamaterial lenses. For example, optical coating layer1312 may include one or more of silicon, titanium oxide, galliumphosphide, or diamond having a thickness in the range of about 150 to450 nanometers. Optical coating layer 1312 may be disposed on bufferlayer 1311 (or on emissive display elements 301-309 and exposed portionsof isolation layer 322 when buffer layer 1311 is not used) using anysuitable technique or techniques such as atomic layer deposition, plasmaenhanced atomic layer deposition, chemical vapor deposition, plasmaenhanced chemical vapor deposition, physical sputtering deposition. Inan embodiment, forming optical coating layer 1312 includes a lowtemperature deposition at a temperature no greater than 400° C. Asdiscussed, the material(s) and thickness of the nanoparticles ofmetamaterial lenses may be a factor in the performance of themetamaterial lenses. In the context of FIGS. 13A-13D, the material(s)and thickness of the nanoparticles of different metamaterial lenses areshared as optical coating layer 1312 is formed uniformly over emissivedisplay elements 301-309. Therefore, the differing properties amongmetamaterial lens properties (e.g., to collimate different wavelengthsof light) may be provided by the size, shape, and pitch of thenanoparticles among the respective metamaterial lenses.

FIG. 13D illustrates an emissive display device structure 1304 similarto emissive display device structure 1303, after the patterning ofoptical coating layer 1312 to form metamaterial lenses 311-319.Metamaterial lenses 311-319 may be patterned from optical coating layer1312 using any suitable technique or techniques such as such as deepultraviolet lithography, extreme ultraviolet lithography, nanoimprintlithography, electron beam lithography, or the like. As shown, thepatterning may provide spacing or gaps between adjacent metamateriallenses 311-319. Furthermore, as discussed, each of metamaterial lenses311-319 may include nanoparticles such as those discussed herein tocontrol the angular emission of emitted light from emissive displayelements 301-309 during operation. The nanoparticles of metamateriallenses 311-319 may include any nanoparticles discussed herein. Forexample, the nanoparticles of metamaterial lenses 311-319 may have across-sectional shape include any or combinations of a circle, an oval,a square, a rectangle, a cross, or a boomerang shape. Furthermore, thenanoparticles of metamaterial lenses 311-319 may have any suitable sizesdiscussed herein.

As discussed, metamaterial lenses 311, 314, 317 (red band lenses),metamaterial lenses 312, 315, 318 (green band lenses), and metamateriallenses 313, 316, 319 (blue band lenses) may have different features suchthat the lenses may selectively control the angular emission of emittedlight of the respective bands of light. In an embodiment, all threetypes of lenses may have different characteristics. In an embodiment,two types of lenses may have the same characteristics and the third lenstype may be different. For example, the lenses may differ in the type(s)of cross-sectional shapes of nanoparticles, the sizes of nanoparticles,the orientations of nanoparticles, or the pitch of the nanoparticles. Inan embodiment, the average size of nanoparticles for metamaterial lenses311, 314, 317 (red band lenses) is greater than the average size ofnanoparticles for metamaterial lenses 312, 315, 318 (green band lenses),which is greater than the average size of nanoparticles for metamateriallenses 313, 316, 319 (blue band lenses). In addition or in thealternative, the average pitch of nanoparticles for metamaterial lenses311, 314, 317 (red band lenses) is greater than the average pitch ofnanoparticles for metamaterial lenses 312, 315, 318 (green band lenses),which is greater than the average pitch of nanoparticles formetamaterial lenses 313, 316, 319 (blue band lenses).

The devices, systems, and fabrication techniques discussed hereinprovide emissive display devices that control the angular emission ofemitted light. For example, the emissive display devices may providecollimated emissive display devices that have low power consumption,high pixel density, full RGB color output, and highly collimated lightoutput. Furthermore, the emissive display devices with integratedmetamaterial lenses described herein may be utilized in display devicesof any type or form factor for any form factor devices. For example, asystem may include an emissive display device having an emissive displayelement and a metamaterial lens over at least a portion of an emissivesurface of the emissive display element such that the metamaterial lensincludes a plurality of nanoparticles, a waveguide optically coupled tothe emissive display device, and first and second holographic beamsplitters disposed on opposite ends of the waveguide as discussed hereinwith respect to FIGS. 1 and 2. In an embodiment, a system may include amemory coupled to a processor, a wireless transceiver, and a displaydevice including any emissive display devices with integratedmetamaterial lenses described herein. For example, the system may be amobile computing platform or device such as a watch, a smartphone, atablet, or a laptop, an augmented reality device, a virtual realitydevice, a headset, or a typically stationary device such as atelevision, a monitor, a desktop computer, or the like.

FIG. 14 illustrates a system 1400 in which a mobile computing platform1405 employs an emissive display device structure, arranged inaccordance with at least some implementations of the present disclosure.Mobile computing platform 1405 may be any portable device configured foreach of electronic data display, electronic data processing, wirelesselectronic data transmission, or the like. For example, althoughillustrated as a tablet, mobile computing platform 1405 may be any of atablet, a smartphone, a phablet, a laptop computer, a watch, anaugmented reality device, a virtual reality device, a headset etc., andmay include a display device 1450 employing an emissive display devicestructure such as emissive display device structure 300 as illustratedin expanded view 1420.

Also as illustrated in expanded view 1420, display device 1450 mayinclude a glass front plate 1425 and a back plane or plate 1430. Forexample, glass front plate 1425 may be disposed adjacent to metamateriallenses 311-319 and may provide protection for components of emissivedisplay device structure 300 and a monolithic display structure for aviewer of display device 1450. Back plane 1430 may similarly provide amonolithic structure for implementing and/or housing emissive displaydevice structure 300 and/or other components of display device 1450. Inan embodiment, a driver circuit is implemented via backplane 1430.Furthermore, glass front plate 1425 and/or back plane 1430 may providecomponents of and/or be provided within a housing of system 1400.

Although illustrated with respect to emissive display device structure300, any suitable emissive display device structure, such as emissivedisplay device structure 1304, may be implemented in display device1450. Furthermore, display device 1450 may provide touch capability viaa capacitive, inductive, resistive, or optical touchscreen. Also asshown, mobile computing platform 1405 includes a chip-level orpackage-level integrated system 1410 and a battery 1415. Althoughillustrated with respect to mobile computing platform 1405, the emissivedisplay device structures discussed herein may also be employed via adisplay of a desktop computer, television, or the like.

Integrated system 1410 may be implemented as discrete components (e.g.,integrated circuits) or as a system on a chip and may include mayinclude memory circuitry 1435 (e.g., random access memory, storage,etc.), processor circuitry 1440 (e.g., a microprocessor, a multi-coremicroprocessor, graphics processor, etc.), and communications circuitry1445 (e.g., a wireless transceiver, a radio frequency integratedcircuit, a wideband RF transmitter and/or receiver, etc.). Thecomponents of integrated system 1410 may be communicatively coupled toone another for the transfer of data within integrated system 1410.Functionally, memory circuitry 1435 may provide memory and storage forintegrated system 1410 including image and/or video data for display bydisplay device 1450, processor circuitry 1440 may provide high levelcontrol for mobile computing platform 1405 as well as operationscorresponding to generating image and/or video data for display bydisplay device 1450, and communications circuitry 1445 may transmitand/or receive data including image and/or video data for display bydisplay device 1450. For example, communications circuitry 1445 may becoupled to an antenna (not shown) to implement any of a number ofwireless standards or protocols, including but not limited to Wi-Fi(IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE 802.20, long termevolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA,TDMA, DECT, Bluetooth, derivatives thereof, as well as any otherwireless protocols that are designated as 3G, 4G, 5G, and beyond.

FIG. 15 is a functional block diagram of a computing device 1500,arranged in accordance with at least some implementations of the presentdisclosure. Computing device 1500 or portions thereof may be implementedvia or mobile computing platform 1505, for example, and further includesa motherboard 1502 hosting a number of components, such as, but notlimited to, a processor 1501 (e.g., an applications processor, amicroprocessor, etc.) and one or more communications chips 1504, 1505.Processor 1501 may be physically and/or electrically coupled tomotherboard 1502. In some examples, processor 1501 includes anintegrated circuit die packaged within the processor 1501. In general,the term “processor” may refer to any device or portion of a device thatprocesses electronic data from registers and/or memory to transform thatelectronic data into other electronic data that may be stored inregisters and/or memory.

In various examples, one or more communication chips 1504, 1505 may alsobe physically and/or electrically coupled to the motherboard 1502. Infurther implementations, communication chips 1504 may be part ofprocessor 1501. Depending on its applications, computing device 1500 mayinclude other components that may or may not be physically andelectrically coupled to motherboard 1502. These other components mayinclude, but are not limited to, volatile memory (e.g., DRAM) 1507,1508, non-volatile memory (e.g., ROM) 1510, a graphics processor 1512,flash memory, global positioning system (GPS) device 1513, compass 1514,a chipset 1506, an antenna 1516, a power amplifier 1509, a touchscreencontroller 1511, a touchscreen display 1517, a speaker 1515, a camera1503, and a battery 1518, as illustrated, and other components such as adigital signal processor, a crypto processor, an audio codec, a videocodec, an accelerometer, a gyroscope, and a mass storage device (such ashard disk drive, solid state drive (SSD), compact disk (CD), digitalversatile disk (DVD), and so forth), or the like. For example,touchscreen display 1517 may implement any emissive display devicestructure(s) discussed herein.

Communication chips 1504, 1505 may enable wireless communications forthe transfer of data to and from the computing device 1500. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. Communication chips 1504, 1505 may implementany of a number of wireless standards or protocols, including but notlimited to those described elsewhere herein. As discussed, computingdevice 1500 may include a plurality of communication chips 1504, 1505.For example, a first communication chip may be dedicated to shorterrange wireless communications such as Wi-Fi and Bluetooth and a secondcommunication chip may be dedicated to longer range wirelesscommunications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, andothers. For example, one or both of communication chips 1504, 1505 mayprovide a wireless transceiver for computing device 1500. As discussed,touchscreen display 1517 of computing device 1500 may include or utilizeone or more emissive display device structures discussed herein.

As used in any implementation described herein, the term “module” refersto any combination of software, firmware and/or hardware configured toprovide the functionality described herein. The software may be embodiedas a software package, code and/or instruction set or instructions, and“hardware”, as used in any implementation described herein, may include,for example, singly or in any combination, hardwired circuitry,programmable circuitry, state machine circuitry, and/or firmware thatstores instructions executed by programmable circuitry. The modules may,collectively or individually, be embodied as circuitry that forms partof a larger system, for example, an integrated circuit (IC), systemon-chip (SoC), and so forth.

While certain features set forth herein have been described withreference to various implementations, this description is not intendedto be construed in a limiting sense. Hence, various modifications of theimplementations described herein, as well as other implementations,which are apparent to persons skilled in the art to which the presentdisclosure pertains are deemed to lie within the spirit and scope of thepresent disclosure.

The following examples pertain to further embodiments.

In one or more first examples, an emissive display device comprises anemissive display element disposed over a substrate and a metamateriallens over at least a portion of an emissive surface of the emissivedisplay element, wherein the metamaterial lens comprises a plurality ofnanoparticles.

In one or more second examples, for any of the first examples, at leasta portion of the plurality of nanoparticles have a cross-sectional shapecomprising one of a circle, an oval, a square, a rectangle, a cross, ora boomerang shape.

In one or more third examples, for any of the first or second examples,each of the plurality of nanoparticles comprises at least one ofsilicon, titanium oxide, gallium phosphide, or diamond.

In one or more fourth examples, for any of the first through thirdexamples, at least a portion of the plurality of nanoparticles have across-sectional shape comprising one of a circle, an oval, a square, arectangle, a cross, or a boomerang shape and/or each of the plurality ofnanoparticles comprises at least one of silicon, titanium oxide, galliumphosphide, or diamond.

In one or more fifth examples, for any of the first through fourthexamples, the emissive display element further comprises a transparentbuffer layer on the emissive surface of the emissive display elementsuch that the metamaterial lens is on the transparent buffer layer.

In one or more sixth examples, for any of the first through fifthexamples, the emissive display element further comprises a secondemissive display element disposed over the substrate, the secondemissive display element to emit a different band of light than theemissive display element is to emit, and a second metamaterial lens overat least a portion of a second emissive surface of the second emissivedisplay element such that the second metamaterial lens comprises aplurality of second nanoparticles, the plurality of nanoparticles have afirst cross-sectional shape and the plurality of second nanoparticleshave a second cross-sectional shape, and the first cross-sectional shapeand the second cross-sectional shape are different.

In one or more seventh examples, for any of the first through sixthexamples, the emissive display element further comprises a secondemissive display element disposed over the substrate, the secondemissive display element to emit a different band of light than theemissive display element is to emit, and a second metamaterial lens overat least a portion of a second emissive surface of the second emissivedisplay element such that the second metamaterial lens comprises aplurality of second nanoparticles and the plurality of nanoparticles aredifferent than the plurality of second nanoparticles.

In one or more eighth examples, for any of the first through seventhexamples, the plurality of nanoparticles have a first cross-sectionalshape and the plurality of second nanoparticles have a secondcross-sectional shape such that the first cross-sectional shape and thesecond cross-sectional shape are different.

In one or more ninth examples, for any of the first through eighthexamples, the emissive display element further comprises a thirdemissive display element disposed over the substrate, the third emissivedisplay element to emit a blue band of light such that the emissivedisplay element is to emit a red band of light and the second emissivedisplay element is to emit a green band of light, and a thirdmetamaterial lens over at least a portion of a third emissive surface ofthe third emissive display element such that the third metamaterial lenscomprises a plurality of third nanoparticles different than theplurality of nanoparticles.

In one or more tenth examples, for any of the first through ninthexamples, the plurality of nanoparticles have a first averagecross-sectional size, the plurality of second nanoparticles have asecond average cross-sectional size, and the plurality of thirdnanoparticles have a third average cross-sectional size such that thefirst average cross-sectional size is greater than the second averagecross-sectional size and the second average cross-sectional size isgreater than the third average cross-sectional size.

In one or more eleventh examples, for any of the first through tenthexamples, the plurality of nanoparticles have a first cross-sectionalshape, the plurality of second nanoparticles have a secondcross-sectional shape, and the plurality of third nanoparticles have athird cross-sectional shape such that the first, second, and thirdcross-sectional shapes are different.

In one or more twelfth examples, for any of the first through eleventhexamples, the emissive display element comprises one of a light emittingdiode, an organic light emitting diode, or a vertical-cavitysurface-emitting laser and the metamaterial lens comprises a collimatingmetamaterial lens.

In one or more thirteenth examples, for any of the first through twelfthexamples, the plurality of nanoparticles comprises a high aspect rationanoparticle having an aspect ratio of a height of the nanoparticle to awidth of the nanoparticle of at least 2.5.

In one or more fourteenth examples, for any of the first throughthirteenth examples, an augmented reality device comprises the emissivedisplay device of any of the first through thirteenth examples,augmented reality optics optically coupled to the emissive displaydevice, and an integrated system coupled to the emissive display deviceand configured to provide image data to the emissive display device.

In one or more fifteenth examples, for any of the first throughfourteenth examples, the augmented reality optics comprise a visuallayer having a prism.

In one or more sixteenth examples, for any of the first throughfifteenth examples, the augmented reality optics comprise a waveguideand first and second holographic beam splitters disposed on oppositeends of the waveguide.

In one or more seventeenth examples, a method for fabricating anemissive display device comprises fabricating an emissive displayelement over a substrate, disposing an optical coating layer over atleast a portion of an emissive surface of the emissive display element,and patterning the optical coating layer to form a metamaterial lenscomprising a plurality of nanoparticles over at least the portion of theemissive surface of the emissive display element.

In one or more eighteenth examples, for any of the seventeenth examples,the method further comprises disposing a transparent buffer layer on theemissive surface of the emissive display element such that disposing theoptical coating layer comprises disposing the optical coating layer onthe transparent buffer layer.

In one or more nineteenth examples, for any of the seventeenth oreighteenth examples, disposing the optical coating layer comprises a lowtemperature deposition at a temperature no greater than 400° C.

In one or more twentieth examples, for any of the seventeenth throughnineteenth examples, disposing the optical coating layer comprises atleast one of atomic layer deposition, plasma enhanced atomic layerdeposition, chemical vapor deposition, plasma enhanced chemical vapordeposition, or physical sputtering deposition and patterning the opticalcoating layer comprises at least one of deep ultraviolet lithography,extreme ultraviolet lithography, nanoimprint lithography, or electronbeam lithography.

In one or more twenty-first examples, for any of the seventeenth throughtwentieth examples, the method further comprises fabricating a secondemissive display element and a third emissive display element over thesubstrate such that the third emissive display element is to emit a blueband of light, the second emissive display element is to emit a greenband of light, and the emissive display element is to emit a red band oflight, such that disposing the optical coating layer comprises disposingthe optical coating layer over at least a portion of a second emissivesurface of the second emissive display element and a portion of a thirdemissive surface of the third emissive display element, patterning theoptical coating layer comprises patterning the optical coating layer toform a second metamaterial lens comprising a plurality of secondnanoparticles over at least the portion of the second emissive surfaceof the second emissive display element and a third metamaterial lenscomprising a plurality of third nanoparticles over at least the portionof the third emissive surface of the third emissive display element, andthe plurality of nanoparticles have a first average cross-sectionalsize, the plurality of second nanoparticles have a second averagecross-sectional size, and the plurality of third nanoparticles have athird average cross-sectional size such that the first averagecross-sectional size is greater than the second average cross-sectionalsize, which is greater than the third average cross-sectional size.

It will be recognized that the embodiments is not limited to theembodiments so described, but can be practiced with modification andalteration without departing from the scope of the appended claims. Forexample, the above embodiments may include specific combination offeatures. However, the above embodiments are not limited in this regardand, in various implementations, the above embodiments may include theundertaking only a subset of such features, undertaking a differentorder of such features, undertaking a different combination of suchfeatures, and/or undertaking additional features than those featuresexplicitly listed. The scope of the embodiments should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed is:
 1. An emissive display device comprising: anemissive display element over a substrate; and a metamaterial lens overthe emissive display element, wherein the metamaterial lens comprises aplurality of nanoparticles comprising a cross-sectional shape of one ormore of oval, square, rectangle, cross shape, or boomerang shape andcomprising a high aspect ratio of height to width of at least 2.5. 2.The emissive display device of claim 1, wherein each of the plurality ofnanoparticles comprises at least one of silicon, titanium and oxygen,gallium and phosphorous, or diamond.
 3. The emissive display device ofclaim 1, further comprising: a second emissive display element over thesubstrate, the second emissive display element to emit a different bandof light than the emissive display element is to emit; and a secondmetamaterial lens over the second emissive display element, wherein thesecond metamaterial lens comprises a plurality of second nanoparticles,and wherein the plurality of nanoparticles have one of a differentcross-sectional shape or size than the plurality of secondnanoparticles.
 4. The emissive display device of claim 1, furthercomprising: a third emissive display element over the substrate, thethird emissive display element to emit a blue band of light, wherein theemissive display element is to emit a red band of light and the secondemissive display element is to emit a green band of light; and a thirdmetamaterial lens over the third emissive display element.
 5. Theemissive display device of claim 4, wherein the plurality ofnanoparticles have a first average cross-sectional size, the pluralityof second nanoparticles have a second average cross-sectional size, andthe plurality of third nanoparticles have a third averagecross-sectional size, wherein the first average cross-sectional size isgreater than the second average cross-sectional size and the secondaverage cross-sectional size is greater than the third averagecross-sectional size.
 6. The emissive display device of claim 1, whereinthe emissive display element comprises one of a light emitting diode, anorganic light emitting diode, or a vertical-cavity surface-emittinglaser and the metamaterial lens comprises a collimating metamateriallens.
 7. The emissive display device of claim 1, further comprising:augmented reality optics optically coupled to the emissive displayelement; and an integrated system coupled to the emissive displayelement device and configured to provide image data to the emissivedisplay element device.
 8. An emissive display device comprising: first,second, and third emissive display elements over a substrate, whereinthe first, second, and third emissive display elements are to emitdifferent bands of light; and first, second, and third metamaterial lensover the first, second, and third emissive display elements,respectively, the first, second, and third metamaterial lensescomprising pluralities of first, second, and third of nanoparticles,respectively.
 9. The emissive display device of claim 8, wherein theplurality of first nanoparticles have a first cross-sectional shape, theplurality of second nanoparticles have a second cross-sectional shape,and the plurality of third nanoparticles have a third cross-sectionalshape, wherein the first, second, and third cross-sectional shapes aredifferent.
 10. The emissive display device of claim 8, wherein theplurality of first nanoparticles have a first average cross-sectionalsize, the plurality of second nanoparticles have a second averagecross-sectional size, and the plurality of third nanoparticles have athird average cross-sectional size, wherein the first averagecross-sectional size is greater than the second average cross-sectionalsize and the second average cross-sectional size is greater than thethird average cross-sectional size.
 11. The emissive display device ofclaim 10, wherein the first emissive display element is to emit a redband of light, the second emissive display element is to emit a greenband of light, and the third emissive display element to emit a blueband of light.
 12. The emissive display device of claim 8, wherein eachof the pluralities of first, second, and third nanoparticles comprise atleast one of silicon, titanium and oxygen, gallium and phosphorous, ordiamond.
 13. The emissive display device of claim 8, wherein theemissive display element comprises one of a light emitting diode, anorganic light emitting diode, or a vertical-cavity surface-emittinglaser and the metamaterial lens comprises a collimating metamateriallens.
 14. The emissive display device of claim 8, further comprising:augmented reality optics optically coupled to the emissive displayelement; and an integrated system coupled to the emissive displayelement device and configured to provide image data to the emissivedisplay element device.
 15. An emissive display device comprising: firstand second emissive display elements over a substrate, the secondemissive display element to emit a different band of light than thefirst emissive display element is to emit; an isolation layer betweenthe first and second emissive display elements; a first metamateriallens over the first emissive display element, wherein the firstmetamaterial lens comprises a plurality of first nanoparticles; and asecond metamaterial lens over the second emissive display element,wherein the second metamaterial lens comprises a plurality of secondnanoparticles.
 16. The emissive display device of claim 15, wherein eachof pluralities of first and second nanoparticles comprise at least oneof silicon, titanium and oxygen, gallium and phosphorous, or diamond,and wherein the isolation layer comprises at least one of silicon andoxygen, silicon and nitrogen, or aluminum and oxygen.
 17. The emissivedisplay device of claim 15, wherein a portion of the first metamateriallens overhangs a portion of the isolation layer adjacent the firstemissive display element.
 18. The emissive display device of claim 15,wherein the plurality of first nanoparticles have a cross-sectionalshape comprising one of a circle, an oval, a square, a rectangle, across, or a boomerang shape.
 19. The emissive display device of claim15, further comprising: a buffer layer between the first emissivedisplay element and the first metamaterial lens and between the secondemissive display element and the second metamaterial lens.
 20. Theemissive display device of claim 15, further comprising: augmentedreality optics optically coupled to the emissive display element; and anintegrated system coupled to the emissive display element device andconfigured to provide image data to the emissive display element device.